This invention relates to a curable two-part electrically insulating composition for the permanent repair of elastomeric cable jackets.
Mining cables, for example, typically utilize an outer jacket material which is elastomeric. Such elastomeric jackets are typically based on neoprene, chlorosulfonated polyethylene, nitrile/polyvinylchloride, and chlorinated polyethylene elastomers.
Currently, one common method of repairing damaged elastomeric cable jackets consists of wrapping a vulcanizable tape over the damaged area, placing the taped area in a suitable sized metal mold, inserting this entire assembly in a heated press and press-curing for a sufficient period of time. It has been found, however, that such vulcanizable tapes have a relatively short shelf life, the process of utilizing same requires considerable skilled labor to properly wrap the tape over the jacket area to be repaired, and considerable energy expenditure is necessary to maintain the heated press continuously at the tape curing temperature.
To overcome these problems, two-part reactive systems have been proposed for use in such cable jacket repair. The two-part system is mixed immediately prior to undertaking the repair, the mixture having a controllable cure time. However, it has been found that such two-part systems do not afford the desired elasticity, toughness, and abrasion resistance to the repaired jacket, and more importantly do not exhibit the requisite adhesion to the elastomeric cable jacket to ensure permanency of repair.
It has now been ascertained that a unique combination of materials can be prepared as a two-part curable system, which substantially alleviates the aforementioned difficulties and further provides the desirable properties of low viscosity and moisture insensitivity prior to curing thereof, together with controllable cure times, necessary electrical insulation characteristics, elasticity, toughness, and abrasion-resistance after curing. In addition, and most importantly, when cast onto elastomeric cable jacket materials for repair thereof, the composition exhibits outstanding adhesion thereto. Furthermore, the composition is capable of curing in a reasonable length of time without necessity of heat. Also, the material can be simply poured into a suitable mold around the cable jacket, thereby simplifying the application and repair procedure.